Gas-blast circuit breaker

ABSTRACT

A contact system for an electrical circuit breaker of the gasblast type includes a tubular stationary contact member and two concentrically arranged tubular movable contact members actuated respectively by piston and cylinder units structurally incorporated into the contact members. In the &#39;&#39;&#39;&#39;make&#39;&#39;&#39;&#39; position of the stationary and movable contact members, the inner one of the movable contact members which is designed as a nozzle abuts the stationary contact member, and the outer one of the movable contact members bridges the abutted contact members and serves to ensure carrying of the current through the circuit breaker contacts. The inner movable contact member is provided with a piston portion slidable in a cylinder formed within the outer movable contact member, and the outer movable contact member includes a piston portion slidable in a longitudinally displaceable cylinder which itself is slidably mounted in a stationary cylinder. During a &#39;&#39;&#39;&#39;break&#39;&#39;&#39;&#39; operation, the outer one of the movable contact members is actuated first within its cylinder, it then entrains the inner one of the movable contact members to separate it from the stationary contact member, and thereafter also entrains its cylinder causing the latter to be displaced within the stationary cylinder. The chamber between the end of the displaceable cylinder and the corresponding end of the stationary cylinder provides pneumatic damping for the displaceable cylinder and the entrained movable contact assembly until the terminal position is reached.

United States Patent Floessel 1151 3,686,453 1451 Aug. 22, 1972 [54] GAS-BLAST CIRCUIT BREAKER [72] Inventor: Carl-Dieter Fislisbach,

Switzerland [73] Assignee: Aktiengesellschaft Brown, Boverie &

Cie., Baden, Switzerland [22] Filed: July 12, 1971 [21] Appl.No.: 161,652

Floess el,

[30] Foreign Application Priority Data Primary ExaminerRobert S. Macon Attorney-Pierce, Schefiler & Parker 5 7] ABSTRACT A contact system for an electrical circuit breaker of 1F fljc the gas-blast type includes a tubular stationary contact member and two concentrically arranged tubular movable contact members actuated respectively by piston and cylinder units structurally incorporated into the contact members. In the make position of the stationary and movable contact members, the inner one of the movable contact members which is designed as a nozzle abuts the stationary contact member, and the outer one of the movable contact members bridges the abutted contact members and serves to ensure carrying of the current through the circuit breaker contacts. The inner movable contact member is provided with a piston portion slidable in a cylinder formed within the outer movable contact member, and the outer movable contact member includes a piston portion slidable in a longitudinally displaceable cylinder which itself is slidably mounted in a stationary cylinder. During a break" operation, the outer one of the movable contact members is actuated first within its cylinder, it then entrains the inner one of the movable contact members to separate it from the stationary contact member, and thereafter also entrains its cylinder causing the latter to be displaced 10 Claims, 3 Drawing Figures PATENTEDwszz m2 SHEET 2 OF 2 Fig.3

GAS-BLAST CIRCUIT BREAKER This invention relates to a gas-blast circuit breaker with a contact system, containing a movable, tubular contact member, having supported therein a trailing bum-off contact member and in which both contact members are pneumatically actuated by means of driving pistons.

It is known in gas-blast circuit breakers, for the hollow contact pin, through which quenching gas. flows, to be provided with av tubular contact member which moves relative to the contact pin and which is advanced during the break operation by the action of a.

spring over the contact pin end facing a mating contact member and which is pushed back, during the make operation, from the mating contact member and against the counteraction of a spring. Such an arrangement is disclosed in German Auslegungschrift 1,156,143. It is also known for the trailing bum-off contact member to be additionally and pneumatically biased in the same direction as the spring. To this end, the bum-off contact member is constructed as a piston, being closed on one side, and being slidably supported in the tubular main contact member, the main contact member being constructed in cylindrical form. with ports for the propelling gas. Such an arrangement is disclosed in Japanese Laid-open Specification 38-22517.

The present invention is based on a gas-blast circuit breaker with a contact system of the kind mentioned hereinabove and it is the principal object of the invention to provide a driving means for the contacts which will establish a rapid motion for the contact members, subject to highly effective damping over a short distance of the motion towards the end of the stroke. In accordance with the invention, this objective is achieved in a simple manner by virtue of the contact member being provided with a reversal collar, movable relative to the contact member which is supported in a movable cylinder component provided with inlet ports, the cylinder in turn being slidably supported in a stationary cylinder so that the cylinder component is entrained by the contact member towards the end of the. make or break movement to effect damping of the motion while the reversal collar prevents the opposite side, in each case, of the contact member driving piston being biased by pressurized gas during the appropriate and related switching movement.

One embodiment of the invention is explained hereinbelow by reference to the accompanying drawings, wherein:

FIG. 1 illustrates a gas-blast circuit breaker with gaspulsed controlled switching means in the on position as a sectional elevation along the line I--I of FIG. 2;

FIG. 2 is a partial cross-section of the switching means shown along the line II-II of FIG. 1; and

FIG. 3 shows the switching means of FIG. 1 in the off position.

With reference now to the drawings and in which like reference numerals designate like parts in the several views, the improved switching means for the circuit breaker is designated in its entirety by numeral 2, and is disposed in an insulated manner, not shown, in the interior of a metallic enclosure 1, as illustrated in FIG. 11. The switching means 2 includes a tubular insulator member 3 having an upper portion of reduced crosssection within which a stationary contact member 4 is 5 joined to a housing 7 which contains an annular gap chamber 8 between two walls thereof, the gap chamber being pennanently connected at the position shown by an arrow, and by means of a duct, not shown, to a vessel containing the arc extinction gas at high pressure. Ports 8a of housing 7 are closed when the circuit breaker is in a steady-state position, e.g. with the contacts closed, and are released during the switching operation by brief opening of a blast valve which is actuated in known manner by a drive through driving rod 9a of which several may be provided.

The closed position of blast valve 9 is indicated in broken lines in FIG. l. The stationary nozzle contact member 5 is adapted to engage a cylindrical nozzle contact member 10. The latter contact member which functions, during a break movement of the circuit breaker, as a trailing burn-off contact, is adapted to slide within a cylindrical hollow main contact member 11. In the make position, the cylindrical contact member I l is engaged with the cup contact member 6, its function being the continuous transmission of current through the contact mechanism of the circuit breaker. Contact member 11 is provided with an expanded part 12 in which the driving piston 10a of the nozzle contact member 310 is adapted to slide. The expanded part 12 is also provided with ports 12a, 12b which can be optionally closed by a reversal collar 13 adapted to slide within a chamber part 12d. Spring 14 is supported between the parts 10a and 13. Part 13 is also provided with several ports 13a.

The expanded part 12 of contact member 11 is slidably supported within the cylindrical part 15 in the manner of a piston l2c. The cylinder part 15 contains ports 15a and in turn is slidably supported within and by an outer cylinder 16. This latter cylinder is stationary and in an appropriate embodiment forms part of the housing 7. It contains inlet ports 16a and 16b.

The method of operation of the contact system is as follows:

The interior of the enclosure 1 and of the switching means 2 is constantly filled with gas at low-pressure, for example SP Ifthe circuit breaker is to be switched off, starting from the make position of FIG. I, blast valve 9 is actuated by the one or more drive rods 9a into the illustrated position so that gas at high pressure can flow from the annular gap chamber 8 into the low-pressure part of the circuit breaker as indicated by the direction of flow arrows. The bottom portion of the expanded part 12, constructed as a piston 12c is thus acted upon by the pressurized gas entering through ports 16a, 15a and ll2a and is thus moved downwardly. Ports 12b will then be closed by the reversal collar 13. At the same time, high-pressure gas passes through port 16b into the chamber 19 below the lower end-face boundary surface of the cylinder part 15 so that compressive damping becomes effective as soon as contact member 11 entrains the cylinder part 15 by means of the expanded part 12 towards the end of the break motion (FIG. 3). A suction damping effect is simultaneously produced over the upper end-face boundary surface when the cylinder part 15 is displaced. The high-pressure gas flowing through ports 16b causes the part 15 to be pushed upwardly until it is entrained. Until being entrained by contact member 11, contact member 10 is pneumatically maintained in engagement with contact member 5 so as to function as a burn-off" contact when it finally leaves the stationary nozzle contact member 5. Chamber 17 communicates through ports 15!; and 160 and ducts 18 with the low-pressure part of the circuit breaker until close to the end of the break motion. During the break motion, the separating contact members and 5 are blown upon in known manner by the high pressure gas, the arc extinction gases which are created being caused to flow through these tubular contact members into the low-pressure part of the circuit breaker.

For the make operation, blast valve 9 is briefly actuated into the open position as illustrated in FIG. 3. As shown by the direction of How arrows, pressurized gas flows (16b, c) below the expanded part 12 and through its port 12b under the reversal collar 13 so that contact member 11 is moved upwardly into the closing position. Chamber 19 above the upper end of the slidable cylinder 15, on the other hand, is filled with pressurized gas through port 16a and recess 15d in the wall of cylinder 15. Reversal collar 13 closes the ports 12a and chamber 20 within cylinder 15 thus communicates through ports 15a, 21 and ducts 18 to the low-pressure part of the circuit breaker.

Towards the end of the make operation, the actions of the chambers 19 and 19' above and below, respectively the end-faces of cylinder 15 are interchanged. Chamber 19 will then become the compression chamber while chamber 19' serves as the suction chamber in performing the damping process. At the same time, any make arc which may occur between the closing contacts is then blown upon in known manner. Contact member 11 is maintained in a defined manner in its two limiting positions by ratchet means which are not shown.

I claim:

1. A gas-blast circuit breaker having a contact system including a movable main contact member and a trailing burn-off contact member both of which are pneumatically actuated by respective piston and cylinder units in relation to a stationary contact member, said main contact member being provided with a relatively movable reversal member and including a piston slidable within a ported displaceable cylinder which is itself slidable in a stationary cylinder, said displaceable cylinder being entrained by said main contact member towards the end of the opening and closing motion of the latter to damp such motion, and said reversal member being operable to prevent the gas pressure which biases the piston of the bum-off contact unit from also exerting on the unit of the main contact a thrust opposing the intended movement of said main contact member.

- 2. A circuit breaker as defined in claim 1 wherein said main contact member is tubular and surrounds said burn-off contact member which is relatively displaceable with respect to said main contact member.

3. A circuit breaker as defined in claim 1 wherein each piston and cylinder unit comprises an axially movable cylinder within which is an axially movable piston integral with one or the other of said movable contact members.

4. A circuit breaker as defined in claim 1 wherein at axially spaced locations a first cylinder within which the piston of the burn-off contact member is movable and a working chamber containing said reversal member, said reversal member being spring-biased away from said first cylinder.

7. A circuit breaker as defined in claim 6 wherein said reversal member is displaceable by pneumatic pressure difference across the piston of said main contact member between two locations at one of which gas under pressure is admitted to one side of the piston of the burn-off contact member from one side of the piston of said main contact member, and at the other location gas under pressure is admitted to said one side of the piston of said burn-off contact member from the other side of the piston of said main contact member.

8. A circuit breaker as defined in claim 1 wherein said stationary cylinder includes damping chambers at each end thereof to cushion terminal motion of the entrained displaceable cylinder to its final position during opening as well as closing of the circuit breaker contacts.

'9. A circuit breaker as defined in claim 1 and which includes a blast valve which opens to admit a blast of compressed arc-quenching gas to said piston and cylinder units as well as to said bum-ofi" contact member.

10. A circuit breaker as defined in claim 1 wherein said stationary and displaceable cylinders include wallports which register with one another to provide at one end-position of said displaceable cylinder a gas flow path leading from one end of said cylinder of the main contact unit to a relatively low pressure region of the circuit breaker, and at the other end-position of said displaceable cylinder a gas flow path leading from the other end of the cylinder of the main contact unit to the relatively low pressure region of the circuit breaker. 

1. A gas-blast circuit breaker having a contact system including a movable main contact member and a trailing burn-off contact member both of which are pneumatically actuated by respective piston and cylinder units in relation to a stationary contact member, said main contact member being provided with a relatively movable reversal member and including a piston slidable within a ported displaceable cylinder which is itself slidable in a stationary cylinder, said displaceable cylinder being entrained by said main contact member towards the end of the opening and closing motion of the latter to damp such motion, and said reversal member being operable to prevent the gas pressure which biases the piston of the burn-off contact unit from also exerting on the unit of the main contact a thrust opposing the intended movement of said main contact member.
 2. A circuit breaker as defined in claim 1 wherein said main contact member is tubular and surrounds said burn-off contact member which Is relatively displaceable with respect to said main contact member.
 3. A circuit breaker as defined in claim 1 wherein each piston and cylinder unit comprises an axially movable cylinder within which is an axially movable piston integral with one or the other of said movable contact members.
 4. A circuit breaker as defined in claim 1 wherein said trailing burn-off contact member is constituted as a nozzle.
 5. A circuit breaker as defined in claim 1 wherein said reversal member is constituted by a collar encircling said burn-off contact member and which is movable within a chamber provided in said main contact member.
 6. A circuit breaker as defined in claim 1 wherein said movable main contact member is provided with an enlargement and has said burn-off contact member extending axially through it, said enlargement providing at axially spaced locations a first cylinder within which the piston of the burn-off contact member is movable and a working chamber containing said reversal member, said reversal member being spring-biased away from said first cylinder.
 7. A circuit breaker as defined in claim 6 wherein said reversal member is displaceable by pneumatic pressure difference across the piston of said main contact member between two locations at one of which gas under pressure is admitted to one side of the piston of the burn-off contact member from one side of the piston of said main contact member, and at the other location gas under pressure is admitted to said one side of the piston of said burn-off contact member from the other side of the piston of said main contact member.
 8. A circuit breaker as defined in claim 1 wherein said stationary cylinder includes damping chambers at each end thereof to cushion terminal motion of the entrained displaceable cylinder to its final position during opening as well as closing of the circuit breaker contacts.
 9. A circuit breaker as defined in claim 1 and which includes a blast valve which opens to admit a blast of compressed arc-quenching gas to said piston and cylinder units as well as to said burn-off contact member,
 10. A circuit breaker as defined in claim 1 wherein said stationary and displaceable cylinders include wall ports which register with one another to provide at one end-position of said displaceable cylinder a gas flow path leading from one end of said cylinder of the main contact unit to a relatively low pressure region of the circuit breaker, and at the other end-position of said displaceable cylinder a gas flow path leading from the other end of the cylinder of the main contact unit to the relatively low pressure region of the circuit breaker. 